1. Field of the Invention
The present invention relates to a magnetic tape cartridge, in which a single tape reel with magnetic tape wound thereon is rotatably housed within a cartridge case and a tape leader pin is coupled with the leading end portion of the magnetic tape.
2. Description of the Related Art
In the magnetic tape cartridges, which are used as storage medium to be employed in external storage units for computers, etc., there is known a type where a single tape reel with magnetic tape wound thereon is rotatably housed within a cartridge case. This magnetic tape is employed as a data archiving tape for computers, etc., and stores important information. For this reason, the magnetic tape cartridge is constructed so that trouble, such as tape jamming, etc., does not occur and that the magnetic tape is not pulled out from the cartridge case unexpectedly.
Also, a tape leader pin is coupled to the leading end of the magnetic tape. When this magnetic tape cartridge is loaded into a recording-reproducing unit, a pin catching member on the side of the recording-reproducing unit engages the tape leader pin and pulls out the magnetic tape from the cartridge case. On the other hand, when the magnetic tape cartridge is unloaded from the recording-reproducing unit, the magnetic tape is wound on the reel and the tape leader pin is returned into the cartridge case by the pin catching member. The tape leader pin is detachably retained in a predetermined position, by a pin retaining spring member provided within said cartridge case so that it faces the tape leader opening of the cartridge case.
The aforementioned tape leader pin is illustrated in FIG. 1A. This tape leader pin P and magnetic tape T are coupled with each other, as illustrated in FIG. 1B. The tape leader pin P is constructed of a pin main body 5 and a clamp member 6, as disclosed in Japanese Unexamined Patent Publication No. 11(1999)-232826. The pin main body 5 is formed, for example, from stainless steel and consists of a tape clamp portion 5a interposed between a pair of inner flange portions 5b, small-diameter portions 5c formed outside the inner flange portions 5b, and outer flange portions 5d formed outside the small-diameter portions 5c. The clamp member 6 is formed, for example, from synthetic resin. This clamp member 6 is equipped with an axial slit 6a and has a C-shaped cross section. The clamp member 6 is inserted elastically on the tape clamp portion 5a of the pin main body 5, and magnetic tape T is clamped between the clamp member 6 and the tape clamp portion 5a. 
FIG. 2 illustrates a conventional magnetic tape cartridge disclosed in Japanese Unexamined Patent Publication No. 2000-36179. Note that in FIG. 2, the right side in the figure is the front side of the cartridge case, because the cartridge case is inserted toward the right side when it is loaded into a recording-reproducing unit.
In this magnetic tape cartridge, a single tape reel (not shown) with magnetic tape T coupled at its leading end with a tape leader pin P is rotatably housed within a cartridge case 4 consisting of an upper case (not shown) and a lower case 3 fastened together by means of small bolts, etc. A tape leader opening 10 for leading the magnetic tape T is formed in one side wall of the cartridge case 4. This tape leader opening 10 is constructed so that it is opened and closed by a slide door (not shown) urged in a closing direction with a spring member (not shown).
The tape leader pin P, coupled with the leading end of the magnetic tape T, and having construction such as that shown in FIG. 1, is inserted in and out of the magnetic cartridge through the tape leader opening 10. The top and bottom walls inside the tape leader opening 10 are provided with pin housing recesses 45 into which the upper and lower flange portions 5d of the leader pin main body 5 are inserted. Also, there is formed an insertion guide portion 21 extending linearly from the pin housing recess 45 toward the tape leader opening 10.
A pin retaining member 50, for detachably retaining the tape leader pin P in the pin housing recess 45, is formed from a plate spring member having a hairpin-shaped cross section. The pin retaining member 50 has an attaching plate portion 50a which extends vertically between the upper and lower cases. The attaching plate portion 50a is clamped between (1) bosses 41 provided on the bottom surface of the top wall of the upper case and the top surface of the bottom wall of the lower case 3 along the inside surface of the case side wall 3b, and (2) the side wall 3b. The pin retaining member 50 further has a pair of upper and lower elastic arm portions 50b which extend from the upper and lower ends of the proximal portion 50d of the attaching portion 50a toward the tape leader opening 10. The outer end portions of the upper and lower elastic arm portions 50b are formed into pin retaining portions 50c, which abut the outer peripheral surfaces of the upper and lower flange portions 5d of the leader pin main body 5.
On the other hand, the pin housing recess 45 of the cartridge case 4 has an abutting surface in the form of a circular arc which receives the outer peripheral surface of the flange portion 5d of the leader pin main body 5. However, the right side portion, on the side of the pin retaining member 50, of the abutting surface has been removed in order to assure installation space for the elastic arm portions 50b and pin retaining portions 50c of the pin retaining member 50.
The tape leader pin P retained in the pin housing recess 45 is pulled out of the cartridge case 4 by a pin catching member 80, called a leader block, which is provided on the side of a recording-reproducing unit. The pin catching member 80 has an engagement cutout 80a which engage with the upper and lower small-diameter portions 5c (see FIG. 1) of the leader pin main body 5. When the engaging operation is performed, the pin catching member 80 first moves linearly in the direction of arrow A toward the tape leader opening 10 and enters the tape leader opening 10 through a side opposite to the case side wall 3b with respect to the tape leader pin P. Then, the outer end of the pin catching member 80 rotates in the direction of arrow B toward the tape leader pin P. The engagement cutout 80a of the pin catching member 80 is caught on the small-diameter portion 5c of the tape leader pin P and is moved back in the direction of arrow C. As a result, the tape leader pin P is pulled out of the cartridge case 4 through the tape leader opening 10. In this manner, the mechanism of the recording-reproducing unit is simplified.
On the other hand, when the magnetic tape cartridge is taken out from the recording-reproducing unit, the pin catching member 80 holding the tape leader pin P advances linearly toward the tape leader opening 10 in the direction opposite to the direction of arrow C. After the tape leader pin P has been retained in the pin housing recess 45, the pin catching member 80 is returned via the tape leader opening 10 along the reverse route of the aforementioned route.
In the tape leader pin P of FIG. 1, incidentally, there is a possibility that the tape leader pin P will be disengaged from the magnetic tape T because of insufficient clamping force, since the coefficient of friction between the magnetic tape T and the pin main body 5 (or the clamp member 6) is low. More specifically, in order to reduce the sliding friction between the magnetic tape T and the magnetic head, a lubricating agent is often coated on the magnetic layer or top surface of the magnetic tape T so that the coefficient of friction is reduced. Similarly, a lubricating agent is coated on the bottom surface of the magnetic tape T. In that case, the coefficient of friction between the pin main body 5 (or the clamp member 6) formed from stainless steel and the magnetic tape T varies with the type of the magnetic tape T. When this coefficient of friction is small, there are cases where the clamping force by the insertion of the clamp member 6 onto the tape leader pin P is reduced.
In addition, when the tape leader pin P is held and pulled out of the tape leader opening 10 of the cartridge case 4 by the pin catching member 80, as described above, the pin catching member 80 is inserted into the tape leader opening 10 in the direction of arrow A and is then rotated in the direction of arrow B to catch the tape leader pin P. For this reason, there is a problem that engagement between the pin catching member 80 and the tape leader pin P cannot be reliably performed, because the tape leader pin P is pushed and moved by the pin catching member 80 when the pin catching member 80 rotates in the direction of arrow B and engages the tape leader pin P.
That is, when the pin catching member 80 rotates in the direction of arrow B and engages the tape leader pin P, there are cases where force is exerted on the tape leader pin P in the direction of arrow B by the pin catching member 80. In such a case, since the right side portion of the abutting surface of the housing recess 45 has been removed, the spring force of the pin retaining member 50 cannot resist the rightward force exerted on the tape leader pin P and therefore the tape leader pin P will be moved out of the pin housing recess 45 or will tilt. As a result, there is a fear that the pin catching member 80 cannot engage the tape leader pin P correctly and the loading operation will not be performed with reliability.
Hence, it has been proposed to provide an abutting portion on a side near the pin retaining member to receive the flange portion 5d of the tape leader pin P and regulate movement of the tape leader pin P during engagement. However, in that case, space for installing the pin retaining member is narrowed, so it becomes difficult to install the hairpin-shaped pin retaining member 50 equipped with the long elastic arm portion 50b. 
To solve this problem, a pin retaining member with a relatively short elastic arm portion can be employed. In that case, if the retaining portion of the outer end of the elastic arm portion of the pin retaining member is forcibly pushed by the tape leader pin P when the tape leader pin P is inserted into the pin housing recess 45 during the unloading operation, there is another problem that plastic deformation will occur near the boundary portion between the attaching portion and short elastic arm portion of the pin retaining member and therefore the short elastic arm portion will no longer return to the original position.
Furthermore, as described in the aforementioned Japanese Unexamined Patent Publication No. 11(1999)-232826, there is a magnetic tape cartridge having separate pin retaining members. The pin retaining members are respectively equipped with elastic arm portions and are independently installed in the upper and lower cases. However, the elastic arm portions of the pin retaining members are equipped at their outer ends with angled pin-retaining portions for retaining the flange portions 5d of the pin leader pin P, and the upper and lower elastic arm portions and pin retaining portions are approximately the same in shape. Because of this, the upper and lower pin retaining members are approximately the same in spring characteristic.
Therefore, when the tape leader pin P is returned into the cartridge case by a pin catching member provided on a drive unit, the upper and lower flange portions 5d of the tape leader pin P are brought into contact with the pin retaining portions of the pin retaining members at approximately the same time and are subjected to approximately the same elastic force. Because of this, the tape leader pin P will be caught on the pin retaining portions and therefore smooth engagement between the tap leader pin P and the pin retaining members will be disturbed.
The present invention has been made in view of the aforementioned circumstances. Accordingly, it is a first important object of the present invention is to provide a magnetic tape cartridge that is capable of enhancing a force of clamping the leading end portion of magnetic tape to a tape leader pin to assure reliability.
A second important object of the invention is to provide a magnetic tape cartridge which is capable of preventing plastic deformation of a pin retaining member during an unloading operation, while assuring a reliable loading operation by preventing movement of a tape leader pin when a pin catching member engages the tape leader pin during a loading operation.
A third important object of the invention is to provide a magnetic tape cartridge which is capable of performing smooth engagement between a tape leader pin and a pin retaining member by preventing a pin catching member from being caught on the pin retaining member when the tape leader pin is returned into a cartridge case.
To achieve the aforementioned objects and in accordance with the present invention, there is provided a first magnetic tape cartridge comprising: a cartridge case; a single reel rotatably housed in the cartridge case, the reel having magnetic tape wound thereon; and a leader pin, coupled with a leading end of the magnetic tape, for leading the magnetic tape;
wherein the leader pin has both a pin main body equipped with a tape clamp portion on which the leading end of the magnetic tape is wound, and a clamp member for fixing the magnetic tape to the tape clamp portion; and
at least either a surface of the tape clamp portion or an inside surface of said tape clamp member is roughened with an average surface roughness Rz of 7 xcexcm or less.
According the first magnetic tape cartridge of the present invention, at least either the surface of the tape clamp portion or the inside surface of said tape clamp member is roughened with an average surface roughness Rz of 7 xcexcm or less. Therefore, even if the surface of magnetic tape has a low coefficient of friction, the roughened surface will enhance the frictional resistance between itself and the magnetic tape and will increase the clamping force between itself and the magnetic tape. Thus, disengagement of the tape leader pin from the magnetic tape can be prevented and reliability can be assured.
In accordance with the present invention, there is provided a second magnetic tape cartridge comprising:
a cartridge case in which a single reel with magnetic tape wound thereon is rotatably housed and a leader pin coupled with a leading end of the magnetic tape is caught by a pin catching member of a recording-reproducing unit and is inserted into a tape leader opening formed in the cartridge case; and
a pin retaining spring member which elastically engages the leader pin so that the leader pin is detachably retained at a predetermined position within the cartridge case;
wherein a wall surface is provided in the cartridge case so that when the leader pin is inserted into the cartridge case, displacement of the pin retaining member due to the engagement of the pin retaining member with the leader pin is regulated within a predetermined range.
In the second magnetic tape cartridge, the aforementioned pin retaining member has an elastic arm portion, and the aforementioned wall surface faces the elastic arm member with a predetermined space and is approximately perpendicular to a direction in which the elastic arm portion is displaced. The predetermined space is set within an elastic limit of the elastic arm portion. Furthermore, the aforementioned wall surface may have a configuration which corresponds to a pin retaining portion formed in an outer end of the elastic arm portion, and may have a protruding portion which faces the pin retaining portion with a predetermined space.
According the second magnetic tape cartridge of the present invention, the wall surface is provided in the cartridge case so that when the leader pin is inserted into the cartridge case, displacement of the pin retaining member due to the engagement of the pin retaining member with the leader pin is regulated within a predetermined range. Therefore, in the case of employing a pin retaining member equipped with a short elastic arm portion which does not require a large installation space, plastic deformation of the elastic arm portion can be prevented.
Therefore, an abutting portion, for receiving the flange portion of the tape leader pin and regulating movement of the tape leader pin during engagement, can be formed in the pin housing recess near the pin retaining member. Thus, even if the tape leader pin is pushed toward the front surface of the cartridge case when the pin catching member engages the tape leader pin during the loading operation, movement of the tape leader pin toward the case front surface can be prevented by the abutting surface formed near the pin retaining member and therefore the tape leader pin can be prevented from being moved out of the pin housing recess or tilting. Since the tape leader pin can be correctly held by the pin catching member, a reliable loading operation can be performed and operational reliability can be assured.
In accordance with the present invention, there is provided a third magnetic tape cartridge comprising:
a cartridge case having upper and lower cases fastened together;
a single reel, rotatably housed within the cartridge case, which has magnetic tape wound thereon;
a leader pin, coupled with a leading end of the magnetic tape, which has upper and lower flange portions at both ends;
upper and lower pin retaining spring members which elastically engage the upper and lower flange portions of the leader pin so that with an axis of the leader pin directed in a vertical direction, the leader pin is detachably retained between the upper and lower cases;
the leader pin being constructed so that it is caught by a pin catching member of a recording-reproducing unit and moved out of the cartridge case and that it is returned into the cartridge case by the pin catching member;
wherein the upper and lower pin retaining members have different spring characteristics so that when the leader pin is returned into the cartridge case, one of the pin retaining members starts engaging with the flange portion of the leader pin earlier than the other.
In the third magnetic tape cartridge of the present invention, the upper and lower pin retaining members may have upper and lower elastic arm portions which differ in at least one of wall thickness, shape, or material so that the different spring characteristics are obtained. Furthermore, the upper and lower pin retaining members may have upper and lower elastic arm portions which are equipped with upper and lower pin retaining portions bent at difference angles so that the different spring characteristics are obtained.
According the third magnetic tape cartridge of the present invention, the upper and lower pin retaining members have different spring characteristics so that when the leader pin is returned into the cartridge case, one of the pin retaining members starts engaging with the flange portion of the leader pin earlier than the other. This can prevent the pin catching member from being caught on the pin retaining member and make possible smooth engagement between the pin leader pin and the pin retaining member.